PRELIMINARY STUDY ON CLASSIFICATION ABOUT DAMAGE DEGREE OF HEMIBERLESIA PITYSOPHILA TO MASSON PINE FORESTS

A classification standard about the damage degree of a new pest Hemiberlesia pitysopkila Takagi to masson pine (Pinus massoniana) forests had been put forward in this paper based on damage characteristics of the pine needles and twigs. The standard included 4 grades:(1)light: more than 80% needles on 2-year-old twigs are green and yellow needles are seldom;(2)middle: about 50%~80% needles on 2-year-old twigs are green and the others are wilt, the twigs slightly bend and wilt;(3)serious: about 50%~80% needles on 2-year-old twigs are wilt, some fall and the twigs wilt obviously;(4)very serious: over 80% needles on 2-year-old twigs are wilt and fall, the twigs wilt severely, some trees appear dying.Through the analysis of comparison between the field classification using the standard above and the differences of volume growth rate of 60 stem analysis, it has been proved that the classification standard has a high accuracy up to 87.73% and it could be used for the pest control.